A large proportion of healthy African Americans have been observed to have a white blood cell count (WBC) that is persistently lower than the normal range defined for individuals of European ancestry [1]â[5].
Energy is only released when chemical bonds are formed. In general, a chemical reaction involves two steps: 1) the original chemical bonds between the atoms are broken, and 2) new bonds are formed. These two steps are sometimes lumped into one event for simplicity, but they are really two separate events.
1 If two substances react and the temperature of the mixture increases, the reaction is exothermic. 2  A chemical reaction involves the breaking of bonds in the reactants and the forming of bonds in the products. 3  It takes energy to break bonds. 4  Energy is released when bonds are formed.t took more energy to break the bonds of the reactants than was released when the bonds in the products were formed. Project the animation Endothermic Reaction. Remind students that a chemical reaction involves the breaking of bonds in the reactants and the making of bonds in the products.